The nozzle block is one of the most important parts of steam turbine. It puts the steam heat energy into kinetic energy and plays a guiding role to the steam flow. The open integral nozzle block is a very unique structure. Due to the restriction of the large steam passage bending degree and the small nozzle mouth, the traditional process is difficult and the production efficiency is low. This paper mainly studies the structure and processing method of a new open integral nozzle block. The difficulties of the manufacturing process are being solved one by one by the way of developing the five-axis NC program, designing the special tooling and making the process technical solution. The process technical solution is to split the whole complex structure into three main parts which are easy to machine. It can easily realize the surface finishing of the steam passage and guarantee the geometric dimension of each steam blade. The surface roughness of the steam passage can reach Ra0.8. The precision requirements for machining and assembling of the open integral nozzle block can be fully met. It has a wide application prospect in promoting the scientific and technological progress of the new structure and the new process.
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